A221468 The Collatz (3x+1) iteration in A220145 converted to decimal.

1, 2, 133, 4, 33, 266, 67733, 8, 541865, 66, 16933, 532, 529, 135466, 135253, 16, 4233, 1083730, 1083717, 132, 129, 33866, 33813, 1064, 8669737, 1058, 2678946987458595510314019806849701, 270932, 270929, 270506, 83717093358081109697313118964053, 32, 69357897

Offset

1,2

Comments

Sequence A005186 tells how many of these numbers are in [2^n, 2^(n+1)-1].

From Rémy Sigrist, Aug 19 2017: (Start)

a(2^n) = 2^n for any n >= 0.

A000120(a(n)) - 1 = A006667(n) for any n > 0.

A070939(a(n)) - 1 = A006577(n) for any n > 0.

All terms are Fibbinary numbers (A003714).

(End)

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Index entries for sequences related to 3x+1 (or Collatz) problem

Mathematica

Table[FromDigits[#, 2] &@ Boole@ OddQ@ Reverse@ NestWhileList[If[EvenQ@ #, #/2, 3 # + 1] &, n, # > 1 &], {n, 33}] (* Michael De Vlieger, Aug 19 2017 *)

Prog

(PARI) a(n) = my (v=0, p=1); while (n>1, if (n%2, n = 3*n+1; v += p, n = n/2); p *= 2); return (p+v) \\ Rémy Sigrist, Aug 19 2017

Crossrefs

Cf. A000120, A003714, A005186, A006577, A006667, A070939, A220145.

Sequence in context: A214436 A135759 A014315 * A327911 A318965 A097641

Adjacent sequences: A221465 A221466 A221467 * A221469 A221470 A221471

Keyword

nonn,base,look

Author

T. D. Noe, Jan 17 2013

Status

approved